(a) Field of the Invention
The present invention relates to a plasma display panel (PDP), and more particularly, to a PDP having discharge cells of differing surface areas in order to improve color purity.
(b) Description of the Related Art
A PDP is a display device that displays images by using a plasma discharge to excite phosphors. In particular, vacuum ultraviolet (VUV) rays emitted from plasma, caused by a gas discharge, excite phosphor layers, which then emit visible light that forms an image. The PDP has many advantages, including: an ability to be used in large screen sizes of 60 inches and greater that have a thin profile of 10 cm or less; a wide viewing angle and good color reproduction; and are less costly and easier to manufacture than LCDs. As a result, the PDP is becoming increasingly popular both in the home and industry.
The PDP structure was first developed in the 1970s. The most common configuration in use today is the triode surface discharge structure. The triode surface discharge structure includes a first substrate having two different types of electrodes, one of which is a scan electrode, grouped in pairs that are formed along a first direction, and a second substrate, which is provided at a predetermined gap from the first substrate, having address electrodes that are formed along a second direction, which is substantially perpendicular to the first direction. A discharge gas is sealed in the gap between the first and second substrates. First, an address discharge of the gas is controlled by the scan electrodes on the first substrate, which are independently operated, and by the address electrodes provided on an opposing surface of the second substrate facing the scan electrodes. Next, a sustain discharge, which controls brightness, is provided by the two-electrode groups disposed on the aforementioned first substrate.
An AC PDP having the conventional triode surface discharge structure is shown in FIG. 5. Address electrodes 115 are formed along one direction (i.e., along the y-axis) on a rear substrate 112, and a first dielectric layer 120 covers address electrodes 115. Barrier ribs 117 are formed on the first dielectric layer 120 defining a plurality of discharge cells 119. Barrier ribs 117 may be formed in a stripe pattern along the y-axis as shown in FIG. 5. It is also possible to utilize other configurations such as a matrix pattern, in which case the barrier ribs include barrier rib members extended along both the x and y-axes. Red, green, and blue phosphor layers 118, respectively, are formed in discharge cells 119, which are defined by barrier ribs 117.
Formed on a surface of a front substrate 111 are a plurality of sustain electrodes is 113, 114, which extend in pairs along the x-axis. Each of the sustain electrodes 113 includes a transparent electrode 113a and a bus electrode 113b, and each of the sustain electrodes 114 includes a transparent electrode 114a and a bus electrode 114b. Sustain electrodes 113, 114 are covered by a second dielectric layer 121 and then an MgO protection layer 123.
Each area between one of the address electrodes 115 and a pair of the sustain electrodes, and delimited by the intersection of these elements corresponds to a position of one of the discharge cells 119.
Due to the electrical inefficiencies inherent in PDP design, the phosphors used in the PDP must be excitable at an energy level lower than the phosphors used in CRTs. This limits the types of phosphors that may be employed in the PDP. Furthermore, there is a significant difference in illumination efficiency (i.e., brightness) between the different red, green, and blue phosphors used in the PDP. This leads to variances in the efficiency and discharge characteristics between the different phosphor colors, which thereby causes difficulties in adjusting white balance, color temperature, and color purity, for example.